Lubricating apparatus of motorcycle engine

ABSTRACT

An engine of a motorcycle is provided with a lubricating apparatus and a crank case within which is mounted a crank shaft having one end extending outwardly from a side wall of the crank case, and a cam sprocket drive gear is mounted upon the crank shaft. A cam chain chamber within which a chain is disposed in a loop is formed upon one side of a cylinder block including a cylinder and a piston and a cylinder head disposed above the cam sprocket drive gear. An oil passage hole is formed within a mating face of the crank case to be mated with the side cover, and an oil passage tube is inserted into the oil passage hole. The oil passage tube has a front end provided with at least one oil jetting hole and extends through an inner space defined by means of the looped cam chain and extends further so as to penetrate the side wall of the crank case so that the oil jetting hole is directed toward a lower surface of the piston when the latter is disposed at a lower dead position from the lower side of the piston so as to jet oil guided through an oil passage formed within mating faces defined between the crank case and the side cover towards the lower surface of the piston. The rear portion of the oil passage tube is provided with an engaging piece so as to firmly secure the tube to the crank case.

FIELD OF THE INVENTION

This invention relates to lubricating apparatus for a motorcycle engine,and more particularly to lubricating apparatus for cooling a piston ofan overhead cam type four-cycle engine.

BACKGROUND OF THE INVENTION

A four-cycle engine mounted upon a motorcycle is usually of the overheadcam type and is provided with a cam chamber within which a cam chain fordriving the cam is accommodated and which is usually integrally formedwithin and with a cylinder block and a cylinder head.

Lubrication for a variable valve mechanism, a large diametered portionof a control rod of the engine cylinder, a bearing portion of the crankshaft, and the like of the engine of the type described above isperformed by means of lubricating oil pumped from an oil pan disposedwithin a lower bottom portion of a crank case by means of an oil pumpthrough an oil passage formed so as to penetrate a thickened portion ofthe crank case and an oil passage composed of a recessed groove formedwithin a mating face of the crank case to be mated with a side cover.

Lubrication inclusive of the cooling of the piston is further performedfor achieving the lubrication between the cylinder and the piston andbetween a small diametered portion of the control rod and a piston pinby properly supplying oil to the lower surface of the piston by suitableoil jetting means.

In accordance with conventional technology, the oil jetting means is, inone arrangement, disposed directly below the lower end of the pistonwhen the same is positioned at a lower dead position and is embeddedwithin the upper end portion of the side wall of the crank case so thatthe front end of the jetting means is directed toward the inner surfaceof the piston through means of a gap defined between the lower endopening of the cylinder and the outer peripheral side surface of thecrank web. The oil is supplied to an oil passage formed so as topenetrate a thickened portion of the side wall of the crank case.

In accordance with another arrangement, the oil jetting means is itselfdisposed at the same position as described with respect to the abovearrangement, but in this arrangement, the oil is supplied to the jettingmeans through means of an oil passage formed within the outer peripheryof a bearing of the crank shaft.

In both of these arrangements, however, since the oil jetting means areembedded within oblique holes or bores formed within the upper endportion of the side wall of the crank case, a drilling working operationis required in order to form the inclined hole, which requires adrilling operation which is different and independent from the otheroperations, resulting in an increase of the usage of additional tools,of the manufacturing processes and, hence, of the manufacturing cost.Furthermore, in a certain case, it may be troublesome to form the oilpassage within the lower portion of the crank case so as to avoid anyinterference with the location of the other members or elements disposedupon the side surface of the crank case.

In accordance with another method for forming the oil passage as apassageway, a recessed groove within the mating faces of a side covermounted upon the side surface of the crank case, for example, a clutchcover, and the crank case. In accordance with this structure, an oilconnection passage is provided for the oil jetting means so as tothereby simplify the entire structure.

However, in the case where the cam chain chamber is disposed between theclutch cover and the side wall of the crank case, it is difficult toprovide the oil passages so as to bypass these portions, and thus thesimplification of the structure of the oil passages even in accordancewith the method described above cannot readily be realized.

OBJECT OF THE INVENTION

An object of the invention is to substantially eliminate the defects ordrawbacks encountered with the conventional technology described aboveand to provide a lubricating apparatus for a motorcycle engine which isparticularly provided with a cam chain chamber and which is capable ofsupplying oil to the lower surface of the piston of the engine unitwhich is located at a lower dead position without forming a complicatedoil passage means, thus improving the workability of the lubricatingapparatus with reduced manufacturing costs.

SUMMARY OF THE INVENTION

The foregoing and other objects can be achieved according to thisinvention by providing a lubricating apparatus for a motorcycle enginein which there is arranged a crank case within which is mounted a crankshaft having one end extending outwardly from a side wall of the crankcase, the extending one end being covered by means of a side cover, acam sprocket drive gear is mounted upon the crank shaft, and a cam chainchamber within which a chain is disposed in the form of a loop betweenthe cam drive sprocket gear and a cam driven sprocket gear is formedupon one side of a cylinder block including a cylinder and a piston anda cylinder head disposed above the cam sprocket drive gear, andcharacterized within that a passage hole is formed in a mating face ofthe crank case to be mated with the side cover and an oil passage tubeis inserted into the passage hole, the oil passage tube having a frontend provided with at least one oil jetting hole extending through aninner space defined by means of the looped cam chain and extendingfurther so as to penetrate the side wall of the crank case so that theoil jetting hole directs a spray of oil toward a lower surface of thepiston when the latter is disposed at a lower dead position from aposition disposed beneath the lower side of the piston so as to jet oilguided through means of the oil passage formed between the mating facesdefined between the crank case and the side cover towards the lowersurface of the piston.

In a preferred embodiment, the oil passage tube is provided with a rearend having a portion bent outwardly normal to the longitudinal axis ofthe oil passage tube and the mating face of the crank case is providedwith an engaging groove which is engaged by the bent portion of the oilpassage tube.

According to the structure described above, the oil can be directlysupplied towards the lower surface of the piston when the same isdisposed at the lower dead position by discharging the oil through meansof the jetting hole formed within the front end of the oil passage tubeinserted within the engine unit through the side wall of the crank casefrom the oil passage formed within the mating faces defined between thecrank case and the side cover. This structure can eliminate the locationof the oil passage at the lower portion of the crank case or within thethickened portion of the side wall of the crank case. The oil passagetube can be inserted into a hole formed normal to the mating face at atime of performing the necessary drilling operations for the screw holesworkability of the lubrication apparatus, that is, the engine unit. Theoil passage tube can be easily removed simply by removing the sidecover, resulting in high maintenance performance characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features, and attendant advantages of the presentinvention will become better understood from the following detaileddescription, when considered in connection with the accompanyingdrawings, in which like reference characteristics designate likecomponents throughout the several views, and wherein:

FIG. 1 is an elevational section of a single cylinder four-cycle engineof a motorcycle;

FIG. 2 is an elevational section taken along the line 2--2 shown in FIG.1;

FIG. 3 is an enlarged sectional view showing mating portions of thecrank case and the side cover of the engine shown in FIG. 1;

FIG. 4 is an enlarged sectional view taken normal to the sectional viewshown in FIG. 3 and within a plane including the oil jetting holes ofthe oil passage tube;

FIG. 5 is a front view of the oil passage tube on an enlarged scaleshown in FIG. 1;

FIGS. 6, 7 and 8 are sectional views taken along the lines 6--6, 7--7and 8--8 shown in FIG. 5; and

FIGS. 9 and 10 are partial elevational sections of conventional pistoncooling devices for a motorcycle engine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In advance of the description of the preferred embodiment of thisinvention, conventional technology in this art field will first bedescribed with reference to FIGS. 9 and 10 for a better understanding ofthis invention.

FIG. 9 is an elevational section of a conventional piston cooling deviceof an engine unit of a motorcycle, and an oil jetting means of thispiston cooling device is disposed directly below the lower end of thepiston 101 which is illustrated as being disposed at a lower deadposition and is embedded within the upper end portion of the side wall104 of the crank case 103 so that the front end of the jetting means 105is directed toward the inner surface of the piston through means of agap defined between the lower end opening of the cylinder 100 and theouter peripheral side surface of a crank web 102. The oil is supplied toan oil passage 106 which is formed so as to penetrate the thickenedportion of the side wall of the crank case.

FIG. 10 shows another arrangement of a conventional piston coolingdevice, the oil jetting means 107 of this example being disposed atsubstantially the same position as that described with respect to theabove arrangement of the jetting means 105 of FIG. 9, but in thisarrangement, the oil is supplied to the jetting means 107 through meansof an oil passage 109 formed within the outer peripheral of a bearing108 of the crank shaft.

In these arrangements of FIGS. 9 and 10, the oil jetting means 105 and107 are embedded within an oblique bore 110 or 111 formed within theupper end portion of the side wall of the crank case by means of thedrilling operation, which must be done in an inclined manner. Thisinvolves troublesome working conditions and defects as described before.

In accordance with another method for forming the oil passage except forthe drilling operation, it is effective to form, as a passageway, bymeans of a mating operation, a recessed groove within the mating facesdefined between a side cover mounted upon the side surface of the crankcase, for example, a clutch cover 112, and the crank case 103. Inaccordance with this structure, an oil connection passage is providedfor the oil jetting means so as to thereby simplify the entirestructure. However, this method also involves a defect in a case wherethe cam chain chamber 113 or 114 is disposed between the clutch coverand the side wall of the crank case for the reason describedhereinbefore. Accordingly, in the conventional piston cooling devices ofthe type shown in FIG. 9 or 10, it is difficult to provide an improvedlubrication means for an engine unit of a motorcycle which has asimplified structure and which can attain the improved function andeffect.

This invention was therefore conceived so as to substantially eliminatethe defects or drawbacks encountered in connection with the prior artdescribed above and will be described in detail hereunder with referenceto FIGS. 1 to 8.

FIG. 1 is an elevational front section of a single cylinder four-cycleengine provided with a lubrication apparatus according to this inventionand FIG. 2 is a sectional view taken along the line 2--2 in FIG. 1.

Referring to FIGS. 1 and 2, a piston 2 accommodated within a cylinder 1is coupled with a crank 4 through means of a control rod 3 and isslidably displaced vertically in the illustrated arrangement insynchronism with the rotation of the crank 4. The crank 4 is supportedupon side walls 7a and 7b of a crank case 6 by means of crank shafts 5aand 5b, which extend outwardly from the side walls 7a and 7b of thecrank case 6, respectively.

A cylinder head 9 is mounted upon a cylinder block 8 within which thecylinder 1 is formed, and the cylinder head 9 is provided with acombustion chamber 10 at the lower portion thereof to which an intakepassage 11 and an exhaust passage 12 are connected so as to be opened orclosed by means of the operations of an intake valve 13 and an exhaustvalve 14. The opening and closing operations of both the valves 13 and14 are controlled by means of the rotations of an intake cam 16 and anexhaust cam 17 journaled within the upper surface of the cylinder head 9by means of the operations of rocker arms 18 and 19.

The cam shaft 15 has one end upon which there is journaled a cam drivensprocket gear 20 which is driven through means of a cam chain 22disposed in an annular loop between the cam driven sprocket gear 20 anda cam drive sprocket gear 21. The cam chain 22 is disposed within a camchain chamber 23 formed within the cylinder block 8 and the cylinderhead 9.

A primary drive gear 24 is mounted upon the crank shaft 5b so as to beengageable with a primary driven gear 26 mounted upon a counter shaft25. The counter shaft 25 is rotated through means of an open-closeclutch 27 and the rotation of the counter shaft 25 is transmitted to adrive shaft 28 through means of a transmission gear mechanism, notshown. Reference numeral 29 designates a drive sprocket gear for theoutput mounted upon the drive shaft 28.

The crank shaft 5b, the cam drive sprocket gear 21, the primary drivegear 24, the primary driven gear 26, the open-close clutch 27, and thecounter shaft 25 are substantially covered by means of the clutch cover30 mounted upon one side of the crank case 6.

As shown in FIGS. 3 and 4, a recessed groove 32 is formed within amating face 31 of the clutch cover 30 to be mated with the crank case 6and the groove 32 constitutes a passageway when the crank case 6 ismated with the clutch cover 30 so that oil fed from an oil pan disposedat the bottom portion of the crank case by means of the operation of anoil pump is guided within the recessed groove 32 formed as a part of theoil passage.

The crank case 6 is also provided with a mating face 33 to be mated withthe clutch cover 30 and, at the mating face 33, an oil passage tube 35is inserted into a through hole 34 disposed parallel to the crank shaft5b at a position above the cam drive sprocket gear 21.

The oil passage tube 35 extends through the inner space of the annularloop arrangement of the cam chain 22 disposed within the vertical plane,as viewed, between the cam drive sprocket gear 21 and the cam drivensprocket gear 20 and further extends so as to penetrate the side wall 7bof the crank case so that the front end of the oil passage tube 35extends outwardly into a gap 37 defined by means of the side surface ofthe outer peripheral portion of a crank web 36 disposed within a loweropened portion of the cylinder 1 directly below the lower edge of thepiston 2 which is illustrated in the lower dead position.

Referring to FIGS. 5, 6, 7 and 8, the oil passage tube 35 has a frontend 35a at which one or more oil jetting holes 38 are formed and therear end 35b of the tube 35 is open. The rear end 35b has a portion bentoutwardly normal to the longitudinal axis of the tube 35 so as to serveas an engaging piece 39 to be engaged with the crank case 6. Asdescribed above, when the oil passage tube 35 is inserted into the crankcase 6, the engaging piece 39 is fitted within an engaging groove 40formed within the mating face 33 of the crank case 6 so that theengaging piece 39, that is, the oil passage tube 35, is positioned andfixed with respect to any rotation thereof about the longitudinal axisthereof and the oil jetting hole 38 therefore always faces the lowersurface of the piston 2 through means of the gap 37. The end face of therear end 35b of the oil passage tube 35 is in registration with themating face 33 so as to communicate with the recessed groove 32.

According to the structure described above, even when the cam chainchamber 23 is defined between the clutch cover 30 and the crank case 6,the oil passage tube 35 is led to a position directly below the lowerdead position of the piston 2 from the clutch cover 30 through the camchain chamber 23 and the cooling oil can be supplied and jetted towardsthe lower surface of the piston 2 through means of the oil jetting hole38. Accordingly, the location of an oil passage within the thickenedportion of the side wall 7b of the crank case 6 can be eliminated, andthe oil is fed to the upper portion of the side wall 7b of the crankcase by way of an oil passage formed within the mating faces definedbetween the crank case 6 and the clutch cover 30, whereby theworkability of the lubricating apparatus itself can be remarkablyimproved with reduced manufacturing cost. In addition, the oil passagetube can be easily removed from the lubricating apparatus by removingthe clutch cover 30, thus easily performing any maintenance thereof.

It is to be understood that this invention is not limited to thedescribed preferred embodiment and many other modifications and changesmay be made without departing from the scope of the appended claims. Forexample in one modification, the arrangement of the oil passage tube maybe arranged upon a side cover such as upon a magnet cover side exceptfor the clutch cover side in the manner substantially identical to thatdescribed hereinbefore. It is therefore understood that within the scopeof the appended claims, the present invention can be practiced otherwisethan as specifically described herein.

What is claimed is:
 1. A lubricating system for an internal combustionengine, within which there is provided a crank case, a crank shaftdisposed within said crank case and having one end thereof extendingoutwardly from a side wall of said crank case, a cover mating with saidside wall of said crank case so as to cover said one end of said crankshaft, a cam drive sprocket gear mounted upon said crank shaft, a camdriven sprocket gear mounted upon a cylinder head of a cylinder blockwithin which a cylinder is defined for reciprocatably housing a pistonof said engine, a cam chain chamber defined within said cylinder blockfor housing a looped chain interconnecting said cam drive sprocket gearand said cam drivn sprocket gear, the improvement comprising:a supportpassage defined within a first portion of said side wall of said carnkcase disposed upon one side of said cam chain chamber; an oil passagedefined within a second portion of said side wall of said crank casewhich mates with said cover and which is disposed upon a second side ofsaid cam chain chamber; and an oil passage tube means, having a firstopen end thereof disposed within said oil passage for receiving a supplyof oil thereform, and a second end thereof disposed within said supportpassage and having at least oen oil jetting hole defined therein,passing through said cam chain chamber such that said second end of saidoil passage tube means has said at least oen oil jetting hole orientedoutwardly from said support passage and toward an interior portion ofsaid cylinder so as to spray oil toward a lower surface portion of saidpiston when said piston is disposed within the vicinity of a lower deadposition within said cylinder.
 2. A lubricating apparatus according toclaim 1, wherein:said oil passage tube means is provided at said firstend with a portion bent outwardly normal to a longitudinal axis of saidoil passage tube means and said second portion o said side wall of saidcrank case is provided with an engaging groove which is engaged by saidbent portion of said oil passage tube means so as to retain said oilpassage tube means within said second portion of said side wall of saidcrank case.
 3. A lubricating system for an internal combustion engine,within which there is provided a crank case, a crank shaft disposedwithin said crank case and having one end thereof extending outwardlyfrom a side wall of said crank case, a cover mating with said side wallof said crank case so as to cover said one end of said crank shaft, anda cylinder block within which a cylinder is defined for reciprocatablyhousing a piston of said engine, the improvement comprising:a supportpassage defined within a first portion of said side wall of said crankcase; an oil passage defined within a second portion of said side wallfo said crank case which mates with said cover; and an oil passage tubemeans, having a first open edn thereof disposed within said oil passagefor receiving a supply of oil therefrom, and a second end thereofdisposed within said support passage and having at least one oil jettinghole defined therein, said second end of said oil passage tube meanshaving said at least one oil jetting hole oriented outwardly from saidsupport passage and toward an interior portion of said cylinder so as tospray oil toward a lower surface portion of said piston when said pistonis disposed within the vicinity of a lower dead position within saidcylinder.
 4. Lubricating apparatus as set forth in claim 3, wherein:saidoil passage tube means is provided at said first end with a portion bentoutwardly normal to a longitudinal axis of said oil passage tube means;and said second portion of said side wall of said crank case is providedwith an engaging groove which is engaged by said bent portion of saidoil passage tube means so as to retain said oil passage tube meanswithin said second portion of said side wall of said crank case. 5.Lubricating apparatus as set forth in claim 1, wherein:said internalcombustion engine is mounted upon a motorcycle.
 6. Lubricating apparatusas set forth in claim 1, wherein:said internal combustion engine is anoverhead cam type four-cylinder engine.
 7. Lubricating apparatus as setforth in claim 1, wherein:said internal combustion engine is mountedupon a motorcycle.
 8. Lubricating apparatus as set forth in claim 1,wherein:said internal combustion engine is an overhead cam typefour-cylinder engine.
 9. Lubricating apparatus as set forth in claim 3,further comprising:intake and exhaust valves operatively mounted withina cylinder head of said cylinder block; a cam shaft rotatably mountedupon said cylinder head and comprising a plurality of cams forcontrolling said intake and exhaust valves; a cam drive sprocket gearmounted upon said crank shaft; a cam driven sprocket gear mounted uponsaid cam shaft; a cam chain chamber defined within said cylinder blockbetween said first and second side wall portions of said crank case; anda cam chain, defining an endless loop, interconnecting said cam drivesprocket gear and said cam driven sprocket gear and disposed within saidcam chain chamber, said oil passage tube means extending through saidcam chain chamber, between said first and second side wall portions ofsaid crank case, so as to extend through said endless loop of said camchain between longitudinally extending side portions of said endlessloop of said cam chain.